Ignition and control system for gas burners



April 21, 1959 c. A. CQBB IGNITION AND CONTROL SYSTEM FOR GAS BURNERS272E TZZEI/ 2- Filed May 25. 1953 U te Statement IGNITION AND CONTROLSYSTEM FOR GAS BURNERS Clifton A. Cobb, St. Joseph, Mich., assignor, bymesne assignments, to Whirlpool Corporation, a corporation of DelawareApplication May 25, 1953, Serial No. 357,265 6 Claims. (Cl. 263-33) Thisinvention relates to improvements in ignition and control systems forgas burners and more particularly relates toa safety igniter circuitwhich has particular application to gas heated clothes driers.

A principal object of my invention is to provide a simplified and novelform of gas burner control circuit utilizing a continuous spark toignite the gas burner.

A. further object of my invention is to provide a safety igniter circuitfor gas burners wherein ignition of the gas burner is attained by amagneto.

Another object of my invention is to provide a gas burner igniter forclothes driers utilizing a magneto driven by the means for driving thedrier drum, to generate a continuous spark to ignite the gas burner.

A further object of my invention is to provide a safety circuitparticularly adapted for gas heated clothes driers, shutting down thegas supply on safety with less unburned gas flow than with theconventional type of units in which the gas burner is ignited by a pilotand the gas flow continues several minutes before going down.

A further object of my invention is to provide a safety igniter circuitfor gas burners utilizing a continuous spark magneto to ignite theburner immediately on the turning on of the gas supply thereto, withoutthe usual Waiting period for warm up by the pilot flame of the usualheat switch connecting the operating solenoid for the burner valve inthe circuit.

A further object of my invention is to provide an igniter circuit forgas burners eliminating the usual safety pilot and the difficultiesheretofore present with such pilots, caused by clogging of the pilot bythe taking on of lint and the like.

Still another object of my invention is to provide a safety ignitersystem particularly adapted for lighting the gas burners of clothesdrying machines in which a magneto is utilized to ignite the main gasburner, and the magneto is driven from the means for driving the drierdrum, assuring that the circuit shut down and the gas burner will not beignited in case the belt to the drier drum should break or run off itssheaves.

These and other objects of my invention will appear from time to time asthe following specification proceeds and with reference to theaccompanying drawing wherein:

Figure 1 diagrammatically shows an automatic igniter circuit and controlsystem for gas burners constructed in accordance with my invention; and

Figure 2 is a diagrammatic view diagrammatically showing the driveconnection to the drier drum and the igniter magneto.

As shown on the drawing:

In the embodiment of my invention illustrated in the drawing, theigniter and control circuit is shown as being operative to control theoperation of a gas heated clothes drier and to ignite the gas burnertherefor, although it need not be in such a circuit and may be utilizedto ignite various types of gas burners used for other purposes. it

The gas drier may be similar to that shown and described in Patent No.2,635,354 which issued to Peter E. Gelhof and Harold E. Morrison onApril 21, 1953, and entitled Gas Heated Drier. The drier and the drivetherefor need only herein be described in suflicient detail to make mypresent invention readily understanda'ble.

A drier drum 10 is diagrammatically shown as being driven from a motor11 by a means of an endless belt drive means indicated generally byreference character 12. A magneto 14 which may be attached to the drierdrum or an idler pulley 18 in the drive to the drier drum is shown ashaving spaced contacts adjacent a main gas burner 15, to provide acontinuous spark there'between during operation of the drier drum 10, toignite themain burner 15 when the supply of gas is turned on. Themagneto 14 may be of any well-known form so need not herein be shown ordescribed in detail.

Electric power to energize the motor 11 and operate: the same, torotatably drive the drier drum 10 is pro-- vided through conductors 16and 17, which may be connected with a suitable source of electric power,which may be the usual outlet in the home.

A door switch 19 is shown as being connected in the conductor 16 and asclosing when the door is closed, to complete a circuit to the motor 11through a contact arm 20 of a timer switch 21, operated by a timer motor22 connected in parallel with the motor 11.

The timer switch 21 may be cam operated and the cams (not shown)operating the timer switch maybe driven through their timing cycles 'bythe timer motor 22. The timer switch 21 may be of any well-known form,so need not be herein described further, except to point out that it hasa second contact arm 23 electrically connected to the contact arm 20 bya conductor 24 and connecting the conductor 16 with the gas burneroperating circuit, as will hereinafter be more fully described as thisspecification proceeds.

The conductor 24 is shown as connecting the contact arm 20 with themotor 11 to energize said motor when the contact arm 20 is in a closedposition. The motor 11 is connected with the conductor 17 through acondoctor 26 and a main line switch 27 An illuminating lamp 29 and agermicidal lamp 30 are shown as being connected from a conductor 16 tothe conductor 17 through the main line switch 27. The illuminating lamp29 and germicidal lamp 30 remain lighted, regardless of whether the dooris open or closed and until opening of the main line switch 2-7.

The contact arm 23 of the timer 21 is shown as connecting the conductors16 and 24 with a limit switch 31 through a conductor 32. The limitswitch 31 may be a conventional form of limit switch operable todeenergize the burner control system upon belt failure. The limit switch31 is connected with contacts 33 of an adjustable thermostat 34. Thethermostat 34 may be a. well-known form of bi-metal thermostatmaintaining a circuit through a thermostatically operated combustionswitch 35 to solenoid coils 36 and 37 of series connected main gasvalves 39 and 40 respectively until the temperature within the drierdrum exceeds the temperature for which the thermo stat is set. Thesolenoid coils 36 and 37 are in turn connected with the conductor 17through a time delay relay or switch 41 and the main line switch 27. Thetime delay a relay 41 may have a bi-rnetal eon-tact arm 42, opening tobreak the circuit through a contact 43 of said switch and the solenoidcoils 36 and 37, upon a predetermined timed delay interval, by theresistor heat created by the energization of a heater coil 44.

The heater coil 44 is shown as being energized through a contact 45 andcontact arm 46 of the combustion switch 35 to open the time delay switchby resistor heat in a pita determined time delay interval, which may beapproximately fifteen seconds;

A gas supply line 47 is shown as delivering gas to a gas cock 49 whichis usually, open and which may be outside of the *drier'corrrpartment;The gas cock 49-is shown asdeliveringgas to a gas regulator 50, whichalso'may be outside of the drier cabinet. The gas regulator 50 mturnisconnected in series with the main gas valves 39 and 40,

for-delivering gas thereto and-to the 'main burner 15'-when" said gasvalves are open;

On the downstream side of the gas valve 40 is a pressure switch 51operatinga contact arm 52, to close a circuit through a contact 53connected with the main line conductors 16 through a conductor 54. Whenthe contact' arm 52 is in engagement with the stationary contact 53,effected by the pressure of the gas passing through the pressure-switch51 to the burner 15, a circuit is completed through a conductor 55 tothe solenoid coils 36 and 37 for the valves 39 and 40, to maintain saidvalves open when In operation of the drier the switch 27 may first beclosed. This will illuminate the illuminating lamp 29 and germicidallamp 30. The drier may then be filled with clothes and the timer switch21 set for the required time cycle. This will move'the contact arm 20into the closed position shown in the drawing, the contact arm 23closing upon operation of the timer motor 22 in a delayed time interval.When the door for the drier cabinet (not shown) is closed, a circuit iscompleted through the contact arm 20 of the timer switch 21 and themotor 11 and timer motor 22 to energize and start said motor and timer.

This effects the drive to the drier drum and the magneto 14 causing themagneto to generate a continuous spark. It will also move the'contactarm 23 to a closed position. Assuming the gas cock 49 to be open and thecontact arm 23 to be in a closed position, an energizing circuit will becompleted through the limit switch 31, contacts 33 of the adjustablethermostat 34, contact arm 46 of the thermostatically operatedcombustion switch 35 andthrough contacts 45 and 56 of said combustionswitch. This will energize the solenoid coils 36 and 37 and open themain gas valves 39 and 40, the circuit being completed through thecontact 43 and contact arm 42 of the time delay relay 41 and the mainswitch 27. The heater coil 44 will also be energized through the contact45 of the combustion switch.

Upon opening of the gas valves 39 and 40, the pressure of gas passingthrough the pressure switch 51 will move the contact arm 52 of saidswitch into engagement with the contact 53 to complete a holding circuitaround the combustionswitch 35 and to maintain the solenoid coils 36 and37 energized.

Assuming the valves 39 and 40 are open and gas is passing through thegas burner 15, the continuous spark generated by the magneto 14 willignite said gas burner. Upon ignition of the gas burner the heat ofcombustion will open the combustion switch 35. This will open thecircuit to' the heater coil 14 and will also open the circuit throughthe contact 56 to the solenoid coils 36 and 37. The solenoid coils36'and 37, however, will be energized through the contact arm 52 andcontact 53 of the pressure switch 51; as previously mentioned' Since thecontact 45 opens upon ignition of the gas burner the heater coil44 willbe deenergiz'ed. This will maintain the contact arm 42 into engagementwith the contact 43'and"maintain .the gas valves 39 and 40:

open.

If, however, the gas burner 15 should fail to ignite,

as by'a-failure'of'themagneto 14, or breaking thedrive' belt for thedrier drum or "for any other reason, the combustion switch 35 willremain closed. The heater coil 44 will then remain energized and openthe time delay relay 41, deenergizing the solenoid coils 36 and 37 andshutting off the gas supply valves 39 and 40 and the supply of gastothe. burner 15'. The pressure-switch 51 will also open.

If at any time during operation of the drier there should be a loss ofgas pressure, the pressure switch 51 willopen' Also, if for any reasonthe gas burner 15 shouldnot' ignite, the combustion-switch35 will remainclosed and the heater coil 44 will be energized and open the time delayrelay 41 and thus close the main gas valves 39 and A new cycle then' 40for the balance of the timed cycle. cannot-be started until the timedelay relay 41 has had time to cool and close its contacts, which may bea mat ter of a few minutes.

In case a belt in the drive to the drier drum 10 should break or-run offits pulleys, the magneto 14 will be inoperative to ignite the gas burner15. When, however,

the drier'is in operation during an active drying cycle and the beltshould break or runofi' 'itspulle'ys, the limit switch 31 will come intooperation and open the circuit to the" solenoid coils 36 and 37 and shutdown the supply of gas to the gas burner 15. The gas burner 15 thencannot be ignited until the belt is repaired and the magneto 14 is againbeing operated by the drive to the drier drum 10. It will be understoodthat various modifications and variations of the present invention maybe eilected without departing from. the spirit and scope of the novelconcepts thereof.

I claim'as my invention:

1. in a gas burnercontrol circuit, a gas supply line, a gas valvetherein, a gas burner on the downstream side of said valve, a magnetofor igniting said burner, a'solenoid coil energizable toopen said gasvalve, an energizing cirwit to said solenoid including a thermallyoperated-combustion switch and a time delay'switch having a heater coilfor opening the contacts of said time delay switch by resistor heat,said thermally operated combustion switch having one set of contactsclosing the circuit to said solenoid coil and havinganother set ofcontacts completing an'energizing circuitto said heater coil and openingboth sets of contacts by the heat of combustion generated upon theignition of said gas burner, and a [pressure switch between said maingas valve and gas burner and having contacts closing a'circuitto saidsolenoid coil upon the passingof gas under pressureto said gas burner,and hc ldingsaid solenoid coil energized upon the opening of saidcontacts of said combustion switch.

2. In a gas burner control circuit particularly adaptable for gas heatedclothes driers having a rotatable drier drum, a main gas line, a shutofl valve in said gas line, a gas burner onthe downstream side of saidshut ofi valve, a=motor, means driving said drier drum from said motor,

a continuously driven magneto driven by the means for saidmshut offvalve including a time-delay switch having contacts normally closed andopening by resistonheat,

a combustion. switchuopening by the-heat of combustion upon the ignitionof said gas burner, a resistor heater inwseries with said combustionswitch for generating heat to open said time delay switch upon failureof said combustion switch to open, and a holding switch by-passing saidcombustion switch and responsive to the passage of gas to said mainburner for holding said solenoid coil energized upon opening of saidcombustion switch upon the ignition of said burner.

3. In a gas burner control circuit particularly adapted for gas heatedclothes driers having a rotatable drier drum, a gas line, a main gasvalve in said gas line, a solenoid coil energizable to open said valve,a gas burner on the downstream side of said gas valve, a motor, meansdriven by said motor for driving said drier drum, a magneto driven bythe means for driving said drier drum and generating a continuous sparkto ignite said gas burner, an energizing circuit for said motor, aninitial energizing circuit to said solenoid coil including a thermallyoperated combustion switch opening by the heat of combustion upon theignition of said gas burner, a time delay switch, and a heater coil forsaid time delay switch opening said switch by resistor heat, said heatercoil connected in said initial energizing circuit in series with saidcombustion switch, and a normal energizing circuit for said solenoidcoil including a holding switch having contacts closing upon opening ofsaid main gas valve and completing an energizing circuit to saidsolenoid coil by-passing said combustion switch and holding saidsolenoid coil energized through said time delay switch upon the openingof said combustion switch.

4. In a gas burner control circuit particularly adapted for gas heatedclothes driers having a rotatably driven drier drum, a motor for drivingsaid drum, a main gas line, a main gas valve therein, a burner on thedownstream side of said valve to provide the heat for drying clothes insaid drier drum, a magneto driven by said motor, an energizing circuitfor said motor, a solenoid coil for opening said gas valve, an initialenergizing circuit to said solenoid including a thermally operatedcombustion switch opening upon the heat of the combustion upon theignition of said burner, a time delay switch having contacts completingan energizing circuit to said solenoid coil and opening by resistor[heat and having a heater coil connected in series with the contacts ofsaid combustion switch and energized through the contacts of saidcombustion switch, and a holding circuit for said solenoid coilincluding a pressure switch completing a circuit to said solenoid coilindependently of said combustion switch through the contacts of saidtime delay switch upon the pressure of gas passing to said burner uponopening of said main gas valve and holding said solenoid coil energizedupon opening of the contacts of said combustion switch.

5. In a gas burner control circuit particularly adapted for gas heatedclothes driers having a rotatable drier drum, a main gas line, ashut-01f valve in said gas line, electrically energizable means foropening said valve, a gas burner on a downstream side of said shut-offvalve, a. motor, means driven by said motor for driving said drier drum,an energizing circuit to said motor including a timer having a timerswitch manually closed to efiect operation of said motor to drive saiddrier drum, an energizing circuit for said electrically energizablemeans to efiect opening of said shut-0E valve to supply gas to gasburner in a predetermined time delay interval after the starting of saidmotor comprising a second timer switch closing after starting of saidmotor, and electrically energizable means energizable upon starting ofsaid motor and prior to energization of said electrically energizablemeans for opening said shut-off valve, for creating a continuous sparkto ignite the gas issuing from said gas burner, comprising a magnetohaving sparking contacts adjacent said gas burner, and a driveconnection from said motor to said magneto for continuously driving saidmagneto as long as said motor is operating, said energizing circuit forsaid electrically energizable means for opening said shut-off valveincluding a combustion switch and a time delay switch for effectingopening of said shutoflf valve through said second timer switch, and aholding switch by-passing said combustion switch and holding saidshut-off valve open through said time delay switch and said second timerswitch upon opening of said combustion switch upon ignition of theburner.

6. In a gas burner control circuit particularly adapted for gas heatedclothes driers having a rotatable drier drum, 'a main gas line, ashut-01f valve in said gas line, electrically energizable meansenergizable to open said shut-01f valve, 2. gas burner on the downstreamside of said shut-01f valve, a motor, a drive connection from said motorto said drier drum, an energizing circuit to said motor including atimer and a timer operated switch manually closed to instigate operationof said motor, an energizing circuit to said electrically energizablemeans for opening said main gas valve to supply gas to said gas burnerafter the starting of said motor comprising a second timer switchclosing after the starting of said motor and a time delay switch havingcontacts normally closed and opening upon a predetermined time intervalupon failure of the burner to ignite, a combustion switch effectingopening of said time delay switch upon failure of the burner to igniteand opening by the heat of the burner flame, a pressure operated holdingswitch holding said electrically energizable means energized throughsaid second timer switch and said time delay switch upon opening of saidcombustion switch by the heat of the burner flame, electricallyenergizable means energizable prior to opening of said shut-off valvefor providing a continuous spark to ignite the gas issuing from saidmain burner comprising a magneto, a drive connection from said motor tosaid magneto for continuously driving said magneto during operation ofsaid motor, and. spaced sparking contacts energized by said magneto andpositioned adjacent said gas burner.

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